Frequently Asked Questions

Question:
My bearded irises are no longer blooming well. Why?
Answer:

The bearded irises may need to be divided.  Bearded irises should be divided every 3 to 5 years as the plants quickly become overcrowded and don’t bloom well.  July or August is the best time to dig, divide, and transplant bearded...

Question:
When should I harvest broccoli?
Answer:

Broccoli should be harvested when the head is fully developed, but before the flower buds begin to turn yellow and open.  At harvest, the terminal head should be tight, blue-green, and approximately 6 to 7 inches in diameter.  Most...

Question:
When should I cut gladiolus flowers for indoor use?
Answer:

Gladiolus for decorative indoor use should be cut as soon as the bottom flower on the spike has opened.  Most of the remaining blooms will open when the spike is brought indoors and placed in water.  When cutting gladiolus flowers,...

Question:
When should I harvest my summer squash?
Answer:

Harvest zucchini and other long-fruited summer squash varieties when the fruit are 1½ to 2 inches in diameter and 6 to 8 inches long.  Scalloped types are best when 3 to 5 inches in diameter.  Fruit should have soft skins (rinds) that...

Question:
How do you propagate forsythias?
Answer:

The forsythia is easily propagated from softwood cuttings. Softwood cuttings should be made from the current season’s growth in late June or early July. Using a sharp knife, cut off 4 to 6 inch long shoots. Pinch off the leaves on the lower half...

Question:
Several leaves on my tomato plant have curled up. Why?
Answer:

The curling of the tomato leaves may be a physiological disorder referred to as leaf roll.  Affected leaves roll upward and inward.  The leaves may also become thickened, giving the foliage a leathery appearance. 

Leaf roll...

Question:
How do I get rid of moles in my yard?
Answer:

Trapping is the best way to get rid of moles.  Trapping isn't easy, but it does work.  Patience and persistence are required.  Traps can usually be found in hardware stores and garden centers.  When using traps, carefully...

Question:
Do I need to remove my grass clippings to prevent thatch development?
Answer:

Grass clippings contribute very little to thatch development because clippings are primarily cellulose and decompose quickly.  There is no need to remove grass clippings when lawns are mowed properly.  Infrequent mowing of tall grass...

Question:
Is it safe to plant currants and gooseberries in home gardens in Iowa?
Answer:

Early in the 1900's, white pine blister rust (Cronartium ribicola) became a serious disease problem in the United States.  White pine blister rust requires both a currant or gooseberry (Ribes species) and white pine to...

Question:
Japanese beetles are devouring my roses. What can I do?
Answer:

Japanese beetles eat the foliage, fruits, and flowers of over 300 plants.  When feeding on foliage, the beetles consume the tissue between the veins, leaving a lace-like skeleton.  Flowers and fruits are sometimes devoured completely....

Question:
I have some small, purplish spots on the canes of my black raspberries. What is it and how can it be controlled?
Answer:

The small, purplish spots are most likely due to anthracnose.  Anthracnose is a serious fungal disease of raspberries, especially black raspberries.  The disease is readily recognized by the small, purplish spots that develop on young...

Question:
When and how do you divide bearded irises?
Answer:

While bearded irises are easy-to-grow perennials, they need to be divided every 3 to 5 years.  If not divided, plants become overcrowded and flower production decreases.  Crowded plants are also more prone to disease problems.  In...

Question:
When should I harvest cabbage?
Answer:

The harvest of cabbage may begin when the heads are firm and the size of a softball.  Mature cabbage should be harvested when the heads are solid and tight, before they crack or split.  Splitting is caused by excessive water uptake; the...

Question:
When can I remove tulip foliage?
Answer:

Tulip foliage should not be removed until it has turned brown and died.  The length of time it takes the foliage to die back depends on bulb type, weather, and other factors.  The foliage of most tulips usually doesn’t die back until...

Question:
The fruit on my zucchini squash began to grow, but quickly turned brown and rotted. Why?
Answer:

The rotting of the small squash fruits could be due to poor pollination or blossom-end rot. 

For squash fruit to develop fully, bees and other pollinators must transport pollen from the male flowers to the female flowers.  If the...

Question:
Should I treat my ash trees to protect them from emerald ash borers?
Answer:

Insecticide treatments are available to protect ash trees from the emerald ash borer.   However, treatments should be undertaken only when necessary to prevent excessive and needless use of insecticides. 

Insecticide treatments...

Question:
When should I harvest okra?
Answer:

Harvest pods when 2 to 4 inches long.  (This is usually 5 to 6 days after flowering.)  Use a sharp knife or hand shears.  Handle the pods carefully as they bruise easily.  Since the pods develop rapidly, it’s often necessary...

Question:
Is there anything that can be done to make my Japanese wisteria bloom?
Answer:

The Japanese wisteria (Wisteria floribunda) is the most widely grown wisteria in the United States.  Unfortunately, it doesn't perform well in Iowa.  Most Japanese wisteria varieties (cultivars) do not bloom when grown in the...

Question:
What is the correct mowing height for a lawn in summer?
Answer:

Kentucky bluegrass and other cool-season grasses thrive in the cool weather of spring and fall.  Hot, dry conditions in summer are stressful for cool-season grasses.  Kentucky bluegrass lawns should be mowed at a height of 3 to 3½...

Question:
What are jostaberries?
Answer:

Jostaberries are a cross between black currants and gooseberries.  Plants are vigorous and may grow to a height of 6 to 8 feet.  Jostaberry fruit are similar in size to gooseberries and black in color.  Plants possess excellent...

Question:
There are yellow-green bugs eating the flowers on my roses. What are they and how can they be controlled?
Answer:

The yellow-green bugs are probably the adults of the northern corn rootworm.  The larvae of the northern corn rootworm feed on the roots of corn plants.  The adults (yellow-green beetles) appear in mid-summer and are present until frost...

Question:
When should I harvest raspberries?
Answer:

Raspberries are ripe when the fruit are fully colored.  Also, ripe berries slip easily from their receptacles, which remain on the plant.  If possible, harvest in the early morning hours before heat builds up in the fruit. ...

Question:
How deep should I plant bearded irises?
Answer:

When planting bearded irises, dig a hole large enough to accommodate the rhizome and roots.  Build a mound in the center of the hole.  Place the rhizome on top of the mound and spread the roots in the surrounding trench.  Then...

Question:
When should I harvest Brussels sprouts?
Answer:

Beginning at the base of the plant, harvest the buds (sprouts) when 1 to 1½ inches in diameter. Continue to harvest the sprouts higher up on the plant as they mature. Sprouts can be stored in a perforated plastic bag in the refrigerator...

Question:
What would be a good planting site for the magic lily?
Answer:

The magic lily (Lycoris squamigera) is a rather intriguing plant.  Other common names include resurrection lily, surprise lily, hardy amaryllis, and naked lady.  The life cycle of Lycoris squamigera is different from...

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